Ignition mounting arrangement in internal-combustion engine

ABSTRACT

A CDI ignition coil unit integrally formed of an exciter coil, pickup coil and control unit is arranged over the upper side of the engine case, at a position on the cylinder head side in proximity to the periphery of the flywheel while an ignition cord is provided to connect a spark plug located at the cylinder head to the CDI ignition coil unit.

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] The present invention relates to an arrangement of aninternal-combustion engine, and in particular relates to an ignitionmounting arrangement in an internal-combustion engine.

[0003] (2) Description of the Prior Art

[0004] Conventionally, magneto ignition systems have been mainlyemployed as the ignition systems of internal-combustion engines havingno battery or other external power supply, such as multi-purpose enginesand small outboard motors.

[0005] Examples of magneto ignition systems include transistor magnetoignition system and CDI ignition system.

[0006] As shown in FIGS. 1 and 2, in a transistor magneto ignitionsystem, a magnet 112 d is disposed at the periphery of a flywheel 112 ofan engine 100 while a core 125 of an igniter 124 is positioned overengine case 113 via spacer 114 so as to oppose the magnet 112 d, whereby a high voltage generated by the igniter 124 is applied to a sparkplug 22 to achieve ignition. This method has the advantage of reducingthe product cost because igniter 124 is low in cost, hence has beenwidely used for multi-purpose engines which are used at a fixed enginespeed.

[0007] On the other hand, in a CDI ignition system, as shown in FIGS. 3and 4, a magnet 222 d is disposed on the inner side of a flywheel 222 ofan engine 200 so as to cause an exciter coil 201 to charge a capacitor(not shown) in a CDI unit 202, whereby a high voltage is applied to aspark plug 22 by an igniter 224 disposednearacylinderhead21 to achieveignition. This method has the advantage of being easy in performingvarious controls because ignition timing can be set freely, hence hasbeen used for engines which need relatively high-performance control. Areference numeral 203 in the drawings designates a pickup coil whichdetects the engine speed.

[0008] However, these conventional ignition systems have the followingdrawbacks. That is, the transistor magneto ignition system suffers aninconvenience that there are cases when the engine speed is low where itis impossible to obtain a high enough generation voltage compared to therequired voltage, failing to provide the spark because variation inmagnetic flux is too small and also there is an inconvenience of thesetting of ignition timing being less flexible.

[0009] For the CDI ignition system, since exciter coil 201, pickup coil203, CDI unit 202 and igniter 224 are all provided separately, thissystem needs more parts compared to the transistor magneto system,resulting in an increased cost.

[0010] In this way, the feature of the ignition system determines thecharacteristic of a conventional magneto ignition engine, either of acost-oriented type or of a high-performance type. Therefore, it has beendifficult to provide development of a series of various models based onone engine base to meet the demands of various users.

SUMMARY OF THE INVENTION

[0011] The present invention has been devised in view of the aboveconventional problems, it is therefore an object of the presentinvention to provide an ignition mounting arrangement in aninternal-combustion engine in which either an inexpensive transistormagneto ignition system or high-performance CDI ignition system can bemounted interchangeably so as to provide a series of various models ofengines such as outboard motors based on one type of engine, wherebyprice difference of the engines due to performance difference can besuppressed.

[0012] In order to achieve the above object, the present invention isconfigured as follows:

[0013] In accordance with the first aspect of the present invention, anignition mounting arrangement in an internal-combustion engine,includes: a flywheel with a magnet, disposed at one end of thecrankshaft; and an ignition coil unit having a generator coil, arrangedclose to the flywheel, wherein the voltage generated by the generatorcoil as the flywheel turns is controlled by the ignition coil unit so asto output a high voltage to a sparkplug, and is characterized in that itis possible to mount as the ignition coil unit either a CDI ignitioncoil unit which is integrally configured of a generator coil, anignition timing detecting means for detecting the ignition timing basedon the rotation of the flywheel and an ignition controller forcontrolling the ignition timing, or a transistor magneto ignition coilunit having approximately the same shape as that of the CDI ignitioncoil unit, and the flywheel to be mounted can be selected in accordancewith the ignition type of the ignition coil unit to be mounted.

[0014] In accordance with the second aspect of the present invention,the ignition mounting arrangement in an internal-combustion enginehaving the above first feature is characterized in that the ignitioncoil unit comprises an igniter and dielectric elements so that thedielectric elements are arranged close to the igniter on both sidethereof, sandwiching the igniter when viewed from the top, and thedielectric elements are positioned outside the flywheel and projectedcloser to the magnet of the flywheel than the igniter is at thepositions where they oppose the magnet.

[0015] In accordance with the third aspect of the present invention, theignition mounting arrangement in an internal-combustion engine havingthe above first feature is characterized in that the engine is used asan outboard motor with the crankshaft arranged approximately verticallyand the cylinder portion directed to the rear,

[0016] the flywheel is fixed at one end of the crankshaft which isprojected outside over the upper side of the engine case so that it canrotate as the crankshaft turns;

[0017] the ignition coil unit is attached to an attachment bossprojected at the top on the upper side of the engine case and isarranged on the cylinder head side along the periphery of the flywheel;and

[0018] an ignition cord is provided to connect the spark plug located atthe cylinder head to the ignition coil unit.

[0019] In accordance with the fourth aspect of the present invention,the ignition mounting arrangement in an internal-combustion enginehaving the above second feature is characterized in that the engine isused as an outboard motor with the crankshaft arranged approximatelyvertically and the cylinder portion directed to the rear,

[0020] the flywheel is fixed at one end of the crankshaft which isprojected outside over the upper side of the engine case so that it canrotate as the crankshaft turns;

[0021] the ignition coil unit is attached to an attachment bossprojected at the top on the upper side of the engine case and isarranged on the cylinder head side along the periphery of the flywheel;and

[0022] an ignition cord is provided to connect the spark plug located atthe cylinder head to the ignition coil unit.

[0023] In the ignition in an internal-combustion engine according to thepresent invention, a CDI ignition coil unit for a CDI ignition systemwhich is integrally formed of a generator coil, an ignition timingdetecting means for detecting the ignition timing based on the rotationof the flywheel and an ignition controller for controlling the ignitiontiming or a transistor magneto ignition coil unit which is designed tobe approximately the same configuration as that of the CDI ignition coilunit, may be used as the ignition coil unit. That is, either ignitioncoil unit can be mounted. Further, the flywheel to be mounted can beselected in accordance with the ignition type of the ignition coil unitto be mounted. Therefore, the inexpensive transistor magneto ignitionsystem and the high-performance CDI ignition system can be mountedinterchangeably on a single engine base. Thus, it is possible to providemultiple models of engines using the same type of engine base, at asharply reduced manufacturing cost compared to the case where multipletypes of engines are manufactured.

[0024] The ignition coil unit is configured so that dielectric elementsare arranged close to an igniter on both side thereof, sandwiching theigniter when viewed from the top. Further, the dielectric elements arepositioned outside the flywheel and close to the magnet located on theflywheel at the positions where they oppose the magnet. When thetransistor magneto ignition system or CDI ignition system is adopted asthe ignition coil unit, either ignition coil unit can be mounted simplyby changing the igniter configuration and the positional relationship ofthe igniter relative to the dielectric elements, without significantlychanging the mounted positions of the dielectric elements and withoutchanging the layout of the other components.

[0025] Moreover, in the engine of an outboard motor with the crankshaftarranged approximately vertically and the cylinder portion directed tothe rear, the flywheel is fixed at one end of the crankshaft which isprojected outside over the upper side of the engine case so that it canrotate as the crankshaft turns while the ignition coil unit is arrangedon the cylinder head side along the periphery of the flywheel.Therefore, it is possible to arrange the ignition coil unit at aposition close to the spark plug and still within the silhouette of theengine from the top, realizing a space-saving layout. Further, since theignition coil unit is attached to an attachment boss projected at thetop on the upper side of the engine case, it is possible to attach itwith simple components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a partially sectional plan view showing an engineconfiguration of a conventional transistor magneto ignition system;

[0027]FIG. 2 is a sectional side view showing the above engineconfiguration;

[0028]FIG. 3 is a partially sectional plan view showing an engineconfiguration of a conventional CDI ignition system;

[0029]FIG. 4 is a sectional side view showing the above engineconfiguration;

[0030]FIG. 5 is a plan view showing an ignition mounting arrangement inan internal-combustion engine in accordance with the embodiment of thepresent invention;

[0031]FIG. 6 is a partially sectional side view showing the above engineconfiguration;

[0032]FIG. 7 is a partially sectional side view showing an outboardmotor employing the above engine;

[0033]FIG. 8 is an illustrative view showing the mounted state of aflywheel and igniter according to the present embodiment;

[0034]FIG. 9A is a plan view showing an igniter configuration of CDIignition according to the present embodiment, FIG. 9B is a side viewshowing the above igniter configuration; and,

[0035]FIG. 10A is a plan view showing an igniter configuration oftransistor magneto ignition according to the present embodiment, FIG.10B is a side view showing the above igniter configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The embodiment of the present invention will hereinafter bedescribed in detail with reference to the accompanying drawings.

[0037]FIG. 5 is a partially sectional plan view showing the overallconfiguration of an engine employing an ignition mounting arrangement inan internal-combustion engine in accordance with the embodiment of thepresent invention. FIG. 6 is a sectional side view showing the aboveengine. FIG. 7 is a sectional side view showing the overallconfiguration of an outboard motor employing the above engine.

[0038] An outboard motor 1 according to this embodiment, as is shown inFIGS. 5, 6 and 7, has an engine 3 mounted on a casing 2 located on thestern of a boat and transfers the driving force of the engine 3 to apropeller 5 located at the bottom end of the casing via a driving shaft4 so as to provide propulsion.

[0039] This engine 3 is a four-cycle transverse engine so arranged thatits crankshaft 6 is laid in the vertical direction while a cylinderportion 7 of a single cylinder is directed rearwards. The lower side ofthe engine, or the casing 2 side is enclosed by a lower cowling 8 andthe upper side is covered by an upper cowling 9.

[0040] Projected outside over the top of an engine case 3 a of engine 3is a top end 6 a of crankshaft 6. A flywheel 12 having an approximatelydown-opening cup-shape is fastened at the top end of crankshaft 6 by abolt 12 f so that it will turn as the crankshaft 6 rotates. On the otherhand, the other end 6 b of crankshaft 6 is coupled to driving shaft 4near casing 2.

[0041] Attached over flywheel 12 is a recoil starter 13 for crankingstart of crankshaft 6.

[0042] The flywheel 12 and recoil starter 13 are enclosed from their topto side or periphery by a starter cover 14.

[0043] The front side, with respect to the direction of travel, of thisstarter cover 14 is projected frontward and outside upper cowling 9 anda starter handle 15 is attached to its end 14 a.

[0044] The ignition system of the internal-combustion engine, includingthe flywheel 12 and a CDI ignition coil unit 20, is arranged on the topof engine 3.

[0045] Next, the ignition mounting arrangement in theinternal-combustion engine will be described.

[0046] As shown in FIGS. 5, 6 and 7, the ignition system configurationof the internal-combustion engine according to this embodiment isconstructed so that CDI ignition coil unit 20 is directly attached to anattachment boss 3 b projected at the top on the upper side of enginecase 3 a and is arranged on the cylinder head 12 side in proximity tothe periphery of flywheel 12 while an ignition cord 23 is provided toconnect a spark plug 22 located at the cylinder head 21 to the CDIignition coil unit 20.

[0047] The flywheel 12 has a boss 12 a at its center, as shown in FIG.8. This boss 12 a has an attachment bore 12 b into which crankshaft 6 isfitted. The attachment bore 12 b is formed with a key slot 12 c, which,in cooperation with a key 6 c, positions flywheel 12 at a predeterminedposition on crankshaft 6.

[0048] Further, the flywheel 12 has a magnet 12 d in part on the outerperipheral side or at a predetermined angular position based on theignition timing so that the magnet will pass over the range where anaftermentioned generator unit of CDI ignition coil unit 20 is disposed.

[0049] The CDI ignition coil unit 20, as shown in FIG. 8, has an igniter24 which includes as a module an exciter coil (not shown) which isexcited by the rotation of flywheel 12, a pickup coil (not shown) fordetecting the ignition timing and a control unit (not shown) for settingup the ignition timing. The unit 20 further includes a pair of coreportions 25 of a dielectric which are arranged substantially parallel toeach other on both sides of igniter 24 so as to sandwich the igniter 24,when viewed from the top.

[0050] These core portions 25 are arranged at positions outside flywheel12, opposing magnet 12 d located at the periphery of flywheel 12 andcloser to the magnet 12 d than igniter 24 is.

[0051] Sparking of engine 3 of this embodiment is effected by generatinga voltage from the generator coil in igniter 24 as flywheel 12 turns,controlling the voltage by the control unit in the igniter andoutputting the high voltage to spark plug 22 via ignition cord 23.

[0052] According to the present embodiment configured as above, sinceCDI ignition coil unit 20 is integrally formed of an exciter coil,pickup coil and control unit so as to configure igniter 24(see FIGS. 9Aand 9B) having substantially the same shape as that of a transistormagneto type igniter 34(see FIGS. 10A and 10B), it is possible toprovide an ignition configuration of CDI ignition by using the analogouslayout of the conventional transistor magneto ignition system.

[0053] Further, since the layout is designed to be analogous to that ofa transistor magneto ignition system as above, it is possible to changethe ignition system into that of a transistor magneto ignition bychanging the igniter and flywheel, whereby it is possible to providemultiple ignition systems in accordance with the necessary enginecharacteristics, based on the same type of engine base.

[0054] In the present embodiment, attachment of flywheel 12 oncrankshaft 6 is positioned and fixed using attachment key 6 c whilemagnet 12 d is arranged at the periphery of the flywheel 12. Therefore,a flywheel of an identical shape which is different only in key slotposition can be used when the ignition mode is changed because both thetransistor magneto ignition type and the CDI ignition type use aflywheel having a magnet at the periphery thereof.

[0055] Thus, a simple change in arrangement makes it possible to adopteither the transistor magneto ignition system or the CDI ignitionsystem. Further, since the cost for die of the flywheel can be reducedand since all the procedures prior to the production step of theflywheel are the same, management cost can be reduced.

[0056] As described heretofore, according to the ignition mountingarrangement in an internal-combustion engine of the present invention,use of an igniter of a CDI ignition coil unit which is substantiallyanalogous in shape to that of transistor magneto ignition by integrallyconstructing an exciter coil, pickup coil and control unit into onemodule, makes it possible to provide a system arrangement of the samelayout as that of transistor magneto ignition.

[0057] By this feature, it becomes possible to provide either CDIignition type or transistor magneto ignition type, based on the sametype of engine base.

[0058] More specifically, for a case where ignition timing may be fixedby giving priority to the cost, the engine configuration of transistormagneto ignition which is inexpensive can be adopted. On the other hand,when it is necessary to provide a high-power engine by controlling theignition timing, or when an engine needs to have multiple functions suchas oil warning, overspeed governor, etc., it is possible to provide ahigh-performance engine using CDI ignition, at a reduced cost.

[0059] Finally, the present invention also makes it possible to modifythe ignition system of an existing engine. That is, it is possible tomodify the ignition system of the engines which have been already sold,from the transistor magneto ignition system into the CDI ignitionsystem, to make some improvements on the engine performances such asincrease in power, exhaust gas treatment, etc., without changing theengine base. In conclusion, it is possible to provide an ignitionmounting arrangement which is excellent in the reduction of costs andresources.

What is claimed is:
 1. An ignition mounting arrangement in an internal-combustion engine, comprising: a flywheel with a magnet, disposed at one end of the crankshaft; and an ignition coil unit having a generator coil, arranged close to the flywheel, wherein the voltage generated by the generator coil as the flywheel turns is controlled by the ignition coil unit so as to output a high voltage to a spark plug, characterized in that it is possible to mount as the ignition coil unit either a CDI ignition coil unit which is integrally configured of a generator coil, an ignition timing detecting means for detecting the ignition timing based on the rotation of the flywheel and an ignition controller for controlling the ignition timing, or a transistor magneto ignition coil unit having approximately the same shape as that of the CDI ignition coil unit, and the flywheel to be mounted can be selected in accordance with the ignition type of the ignition coil unit to be mounted.
 2. The ignition mounting arrangement in an internal-combustion engine according to claim 1, wherein the ignition coil unit comprises an igniter and dielectric elements so that the dielectric elements are arranged close to the igniter on both side thereof, sandwiching the igniter when viewed from the top, and the dielectric elements are positioned outside the flywheel and projected closer to the magnet of the flywheel than the igniter is at the positions where they oppose the magnet.
 3. The ignition mounting arrangement in an internal-combustion engine according to claim 1, characterized in that the engine is used as an outboard motor with the crankshaft arranged approximately vertically and the cylinder portion directed to the rear, the flywheel is fixed at one end of the crankshaft which is projected outside over the upper side of the engine case so that it can rotate as the crankshaft turns; the ignition coil unit is attached to an attachment boss projected at the top on the upper side of the engine case and is arranged on the cylinder head side along the periphery of the flywheel; and an ignition cord is provided to connect the spark plug located at the cylinder head to the ignition coil unit.
 4. The ignition mounting arrangement in an internal-combustion engine according to claim 2, characterized in that the engine is used as an outboard motor with the crankshaft arranged approximately vertically and the cylinder portion directed to the rear, the flywheel is fixed at one end of the crankshaft which is projected outside over the upper side of the engine case so that it can rotate as the crankshaft turns; the ignition coil unit is attached to an attachment boss projected at the top on the upper side of the engine case and is arranged on the cylinder head side along the periphery of the flywheel; and an ignition cord is provided to connect the spark plug located at the cylinder head to the ignition coil unit. 